Devices are known for gripping the external wall surface of a pipe, which include a body having an internal tapered wall part, and a cage with balls or rollers cooperating with the tapered wall part thus to move inwardly and grip the pipe wall to prevent its removal from the device. In such devices the cage is spring-loaded in a direction to cause the balls or rollers to grip the wall but in many such examples when fluid pressure is applied within the device there is a tendency for the pipe to slip and move longitudinally by as much as 5 mm or more. This movement causes the balls or rollers to become partially embedded in the pipe wall, which makes it difficult subsequently to remove the pipe from the device and it is often a disadvantage that the external wall of the pipe is partially deformed or scored by the balls or rollers.